Abstract:
Estimation of ionospheric behavior ahead of sending signal to devices on Earth or
on space vehicle is significantly important for making correction on the signal to
be transmitted. The equatorial ionosphere is basically affected by photoionization,
-t -t
(E x B) drift, .:neutral wind and equatorial irregularities. However, these effects
are highly dependent on th'e level of solar activity. Therefore, in the present study
, -
correlations of daily solar activity indices (FlO. 7 and R) with their corresponding daily
mean GPS TEC deployed at Bahir dar (ll.6°N and 37.36° E), Ethiopia in the year
2013 have get special attention. Hence th.,e _coefficient of determination (r2)has been
-calculated -in between the daily mean data of vTEC and solar parameters as well as
in between observed vTEC and model vTEC. Moreover preparation of suitable model
~ as a function of sunspot number and Fl0.7 that can describe the actual measurement
"
have been employed via quadratic curve fitting. So as to produce best quadratic
curve fitting, pertinent coefficients (quadratic and linear) and extrapolation points
_,..
are calculated. This work confirms the presence of higher coefficient of determination
in between solar activity indices and vTEC during April, May and September than
June, July and August. More practically r2 is calculated as (0.69, 0.78),(0.73, 0.57)
...
- '
-and (0.77, 0.75) for April, May and September as well as (0.2, 0.3), (0.41, 0.18) and
(0.58, 0.46) for July, August and June in between vTEC and Fl0.7 as well as between
....
vTEC and R respectively. In ac.ldition to this both saturation and amplification trend
of the model vTEC versus solar activity indices were observed more frequently than
linear trend of v<l'fiation across the months of the year considered .
.
Key words: Ionosphere; vertical TEC; solar activity indices.
